一个OpenGL的基本实例。对于初学者很有入门意义，只需要看懂即可对OpenGL有较深刻的体会。在以后的学习中，此程序还可以作为模板，添加代码即OK-A basic example of OpenGL. Introduction for beginners is very significant, just read you can have a more profound for OpenGL experience. In the later study, this program can a